Chronic lung disease in children is a serious problem; the two-year mortality is 35% on full contemporary medical and pharmacological management. Recovery by growth and remodeling occurs but is limited by impaired gas exchange and pulmonary hypertension. Lung transplantation is the only definitive treatment, and is feasible but rarely practiced. One of the major limitations is the lack of an artificial lung bridge to transplantation. Over three decades we have developed the extracorporeal artificial lung (ECMO) from laboratory to clinical research to mature clinical practice. This research has been supported by the current grant (HD 15434) since 1981. This is a continued renewal application for that grant. ECMO is effective for acute respiratory failure but because of complexity is not applicable to chronic respiratory failure bridging to lung transplantation in children. Over the lat decade we addressed this problem for adult respiratory failure resulting in the development of an implantable artificial lung which is now routinely used successfully as a bridge to transplantation. The goal of the proposed research is to develop an implantable artificial lung for children which can serve as a bridge to recovery or transplantation.